<template>
	<ul class="list">
		<li class="item"
			v-for="item of letters"
			:key="item"
			:ref="item"
			@click="handleLetterClick"
			@touchstart.prevent="handleTouchStart"
			@touchmove="handleTouchMove"
			@touchend="handleTouchEnd"
			>{{item}}</li>

	</ul>
</template>

<script>
export default {
  props: {
    cities: Object
  },
  name: 'CityAlphabet',
  computed: {
    letters () {
      const letters = []
      for (let i in this.cities) {
        letters.push(i)
      }
      return letters
    }
  },
  data () {
    return {
      touchStatus: false,
      startY: 0,
      timer: null
    }
  },
  updated () {
    this.startY = this.$refs['A'][0].offsetTop
    console.log(this.startY)
  },
  methods: {
    handleLetterClick (e) {
      this.$emit('change', e.target.innerText)
    },
    handleTouchStart () {
      this.touchStatus = true
    },
    handleTouchMove (e) {
      if (this.touchStatus) {
        if (this.timmer) {
          clearTimeout(this.timer)
        }
        this.timer = setTimeout(() => {
          const touchY = e.touches[0].clientY - 79
          const index = Math.floor((touchY - this.startY) / 22)
          if (index >= 0 && index < this.letters.length) {
            console.log(this.startY)
            this.$emit('change', this.letters[index])
          }
          console.log(index)
        }, 16)
      }
    },
    handleTouchEnd () {
      this.touchStatus = false
    }
  }

}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl'
.list
	display:flex
	flex-direction:column
	justify-content:center
	position:absolute
	top:1.58rem
	right:0
	bottom:0
	width:.4rem

	.item
		line-height:.44rem
		text-align:center
		color:$bgColor
</style>
